Background Concentration of Pollutants

Abstract

Determining background concentration of pollutants in surface and groundwaters is a particularly difficult task, but a most important one because of the definition of water quality standards. The major difficulty resides in the dynamic nature of pollutant dispersion and persistence in water systems and its individual characteristics, thus making it sometimes hard to distinguish between contaminated and uncontaminated samples based in one or a limited number of elements. The factors that determine the water chemistry are briefly discussed with some relevant examples, because it is essential to understand global water chemistry. A distinction between background concentration of inorganic and organic pollutants is made, which is because the former can have both natural and anthropogenic derived sources, whereas the latter are exclusively because of anthropogenic activities. In either case, determining background concentrations requires a representative set of water samples unaffected by factors that can change an element's concentration considerably in that system. These samples should preferably be taken in the same area, or at least in similar geological contexts. When this is not achieved satisfactorily, the use of probability plots or geostatistical methods, such as factorial kriging, may be possible solutions to the problem. Keywords: inorganic pollutants; organic pollutants; remediation; biodegradation; trace elements; drinking water standard; sampling; probability plots; factorial kriging; uncontaminated samples; anthropogenic impacts